1. Field of the Invention
The present invention generally relates to a vehicle steering system for steering wheels of a vehicle. More specifically, the present invention relates to a steering system that provides for widening the maximum steering angle without enlarging the wheel housings of the vehicle.
2. Background Information
Generally, there are two basic types of steering systems used on passenger cars: manual and power. In a manual steering system, the driver's effort to turn the steering wheel is the primary force that causes the front steerable wheels to turn to the left or right on steering knuckles. With power steering, the driver's turning efforts are multiplied by a hydraulic or in electro hydraulic assist. Whether the steering system is a manual steering system or a power steering system, one of the most common types of steering system is a rack-and-pinion type steering system. A typical rack-and-pinion steering system basically includes a pinion shaft, a rack gear, a gear housing, two tie rod assemblies and two steering knuckles.
When a wheel turns around a kingpin or steering axis, generally one part of the wheel shifts its position inward in the widthwise direction of a vehicle. In the meantime, the other part of the wheel shifts outward of the vehicle. Therefore, if the steering angle becomes larger, the wheel contacts the wheel housing.
The wheel housing can be widened in the widthwise direction in order to avoid the contact and therefore the maximum steering angle can be larger. However, it will be impossible to mount a large engine or a large transmission by sacrificing the space for the wheel housing. On example of a vehicle steering system that attempts to widen the maximum angle of the steerable wheels without enlarging wheel housings is disclosed in Japanese Laid-Open Publication No. 6-219314. The vehicle steering system disclosed in this Japanese publication is designed to widen the maximum steering angle of the steerable wheel disposed on the outside of the vehicle's turn radius, even when the steerable wheel disposed on the inside of the vehicle's turn radius reaches its maximum angle, by installing an expansion and contraction mechanism in each of the links that are attached to the knuckle arms.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved vehicle steering system. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.